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CHAPTER 1

INTRODUCTION TO THE COMPANY

1.1 ABOUT THE COMPANY

The ACME Group is a leader in the field of energy management and innovative solutions for

the wireless telecommunications and alternate energy sector. It prides itself as a pioneer in

the development of green technology solutions that environmental friendly, energy efficient,

& cost effective that are capable of delivering a quick return on investment. The ACME

group is a result of the vision and commitment of its founder, Mr. Manoj Kumar Upadhyay.

He sought to realise this goal by providing radically new technology solutions through

intensive research and development instead of making incremental changes to existing

technologies. The establishment of ACME Tele Power Limited in 2003 was the first step

towards realisation of this dream.

Today ACME products are installed over 1,50,000 telecom sites across the globe. ACME

products helps Carbon Emission Savings of 2.2 Million Tonnes Per Annum. ACME has

enabled telecom expansion to farthest as well as most interior and hitherto unconnected

regions of India while reducing carbon emissions from the telecom site as well. The

Company today enjoys an international presence, through its own establishments, channel

partners, and associates. In 2004, Manoj Kumar Upadhyay developed the Power Interface

Unit (PIU) to create an industry in itself. Since then several innovation through external and

internal collaborations shaped the company's future. ACMEs has a proven track r ecord of providing innovative solutions

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Fig 1

ACME has embraced latest innovation like cloud computing and LED based Network

Operations Center a mong many other IT technologies, some of them first in the country, to

ensure the workforce spread across the length and breadth of the country is empowered and

highly productive.

Telecom vertical provides comprehensive energy management products and solutions to

wireless telecom players both in India as well as overseas. The Innovative products and

Solutions are backed by empowered field organization, spread across 17 countries. The wide

range of products provides cost-effective, energy-efficient, integrated, end to end passive

infrastructure solutions.

The telecom site performance is optimized to cut energy costs and operational costs

leveraging remote monitoring systems and analytics powered by the worlds largestknowledgebase of passive infrastructure performance leading to higher EBITDA and

Margins.

ACME owned towers boast of innovative alternative energy solutions to power the sites such

as the DC Power House, Solar panels etc.

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ACME is the only organization to successfully integrate designing, manufacturing, installing

and operating capabilities for telecom sites, thus making seamless telecom connectivity

possible in a country as geographically spread as India.

ACME has enabled telecom expansion to farthest as well as most interior and hitherto

unconnected regions of India while reducing carbon emissions from the telecom site as well.

The Company today enjoys an international presence, through its own establishments,

channel partners, and associates.

TELECOM POWER

Fig 2

ACMEs power generation products help telecom companies to manage disproportionatelyhigh costs of diesel and conventional energy costs. The wide range of products include DC

Power House, a clean energy source that directly provides stable DC power eliminating the

need for inefficient AC to DC conversion devices at telecom sites, Fuel Cells that are reliable

and high quality source of power offering the ease of modularity and scalability, Hybrid

power solutions with large battery backups and solar integration. The power generation

systems can be remotely monitored, optimized and controlled.

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1.3 Acme Future Energy Management

Fig 3

1.3 VALUES

It is important for organizations to have values for which they stand. At ACME, it is these

values which define and guide us.

Customer Centric

We empathize with our 'Customers' and deliver solutions that surpass their expectations.

Innovation

we relentlessly deliver innovative and path-breaking products, processes, services and

business solutions.

Respect

we 'respect' every individual. We promote an open and engaged environment that reflects

empathy and fairness. We reward only performance.

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Continuous Learning

we transform all stakeholders (employees, customer, shareholders, partners and community)

through continuous learning to enable them to achieve their qualitative and quantitativegoals.

Execution Excellence

We meet our commitments and create global benchmarks in Execution Excellence in allthat we do.

1.4 ENVIRONMENT POLICIES

As the world moves more and more towards urbanization, the importance of built

environment is also increasing. This however puts a heavy burden on Earths resources.For example, buildings globally consume over 40% of all the energy. ACME with its vision of

being the global benchmark for green energy solutions has a suit of offerings to help make

your built environment greener. Our current areas of focus in the Built Environment are the

Buildings and the Cold Chain, for these sectors, we offer solutions that cut across the energy

value chain. Namely, Supply, Monitoring and Demand. We can make your captive power

generation more efficient and provide alternate and renewable energy source solutions, help

monitor and manage your energy generation and consumption. On the demand side we have

green cooling systems for buildings and green panelling solutions for cold chain

1.5 EVOLUTION

Acme was incorporated as Acme Tele Power Private Limited on January 14, 2003under the Companies Act, 1956, as amended. It was converted into a public limited

company with effect from August 29, 2005.

ACME Tele power Ltd shortlisted for Green Mobile Award for Best Green Product/Service or Performance category by GSMA (Mobile World Congress 2011).

New Delhi, February 28th, 2011: ACME Tele Power Ltd exhibited M50

(compressor-less green air conditioner) and H80 (green hybrid air conditioner) at

ACREX 2011 Exhibition which was held at Pragati Maidan, New Delhi, India

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between February 24th 26th, 2011. ACME won the coveted ACREX Award of Excellence 2011 in the Green product category.

ACME in technical collaboration with Coolerado Corporation, USA

(www.coolerado.com) offers a range of green air-conditioning solutions for various

indoor cooling applications for commercial and industrial spaces.

Acme Tele Power has become the first Indian company to get a five on five IPO

rating, with rating and research firm Crisil on Wednesday assigning the highest grade

to the companys proposed public issue of 1.7 crore equity share.

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CHAPTER 2

VARIOUS ACME PRODUCTS

2.1 PIU:- Power Interface Unit

Acme tele power ltd. Manufactures and exports the power interface unit. This provides

complete ac power management for telecom sites including voltage, phase selection and

surge protection. The product employs static, electronic parts which require lower

maintenance compared with traditional mechanisms. It integrates all essential components of

a site into a single compact rack to support total automation. Acme tele power holds a patentfor this product until 2024.

Telecommunications shelters and towers are vulnerable to various environmental and power-

related hazards such as lightning and voltage surges. The occurrence of lightning is a random,

chaotic and dangerous act of nature. It is an unpredictable event, whose effects can be direct

or indirect. During lightning, pulses of amplitude 200 ka with wave shape of 10/350 microns

are generated.

Acme tele power ltd. Presents lightning and surge protection to telecommunication

equipment. It offers a dynamic, external lightning protection device, which is radio quiet and

its operation only occurs during lightning. Acme also provides internal lightning and surge

protection systems.

Lightning flashes have been graded, representing that they can reach temperatures to the tune

of 30,000 degrees Fahrenheit or more.

Advantages

Greater energy efficiency than that which is typical for the combined efficiency of a

servo stabilizer and an isolation transformer

Compact size reduces overall shelter size, which in turn results in smaller ac and dg Requirements, less wiring and reduced interconnection, resulting in faster installation Auto phase selection and half cycle voltage correction, also increases utilization of

incoming mains resulting in less use of generators

Employs static electronic parts which require lower maintenance compared with

traditional mechanisms

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Product technology and software can be customized based on client needs with over

30 available versions

Availability of full service solution and maintenance services

Remote monitoring, and smoke and intruder protection 70,000 working hours prior to failure [approximately 12 years] and longer life spans

compared to standard industry products.

2.2 Line Conditioning unit :- Line Conditioner Unit (LCU) provides variablereplacement of standard servo stabilizers, immensely benefitting the industry. It helps

to manage unbalanced loads and low-power factor loads like motors, sodium lamps,

etc.

2.3 Free Cooling unit :- FCU reduces the AC running hours on the telecom sitewhenever ambient temperature is lower than the shelter temperature.

2.4 Green Shelters :- Green Shelter is an integrated, tailor-made and end-to-end

energy management solution to minimise energy needs at site resulting in power savings

of 3120 unit per year per site. The shelters come as riveted shelters, rivetless shelters,

liftable shelters.

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CHAPTER 3

INTRODUCTION TO POWER INTEFACE UNIT

Power Interface Unit, which is commonly known as PIU, is the most modern electrical

interface and control unit used for GSM / Telecom installation. The system is intended to

be used for replacement of Servo Stabilizer, AMF Panel, Isolation Transformer, AC

Distribution Panel, Lightning and Surge Arresters, Alarm Panel, Generator Battery

Charger, etc. at telecommunication site.

The advance feature of the unit provides input voltage correction in s to enable the user to utilize the mains even under extreme low voltage conditions which servo technology

was not able to offer due to slow response. The input voltage is isolated completely. The

unit has very fast true RMS measurement with High and Low voltages disconnect facility.

Fig 4

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Lightning and Surge Protector

Fig 5

Telecommunications shelters and towers are susceptible to various environmental and power-

related hazards such as lightning and voltage surges. The phenomenon of lightning is a

random, chaotic and dangerous act of nature. It is an unpredictable event, whose effects can

be direct or indirect. During lightning, pulses of amplitude ~200 KA with wave shape of

10/350 microns are generated. ACME Tele Power Ltd. provides lightning and surge

protection to telecommunication equipment. It offers a dynamic, external lightning protection

device, which is radio quiet and its operation only occurs during lightning. ACME also

provides internal lightning and surge protection systems. Lightning flashes have been graded,

indicating that they can reach temperatures to the tune of 30,000 degrees Fahrenheit or more.

IEC 61312 maintains that despite having a proper earthing system, 50% of lightning charge

enters the system through power lines, telecom data lines and water gas pipes. In other words, if 200 KA lightning strikes and is grounded, half of it is absorbed by the earth. Yet,

the potentially damaging charge of approximately 100 KA would return to the system

through the grounding loop.

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3.1 The Power Interface Unit (PIU) has the following sub units :

1) Input Interface & Protection Panel

2) AC Distribution Panel3) AMF &Interlock Panel

4) Static Line Conditioner

5) Alarm Interface

6) Central Supervisory Unit

1) Input Interface & Protection Panel

The Generator input interface panel provides the user termination for mains, Generator, Unit

& power Earthing. The panel also accomplishes lighting arresters.

A) Auto Phase Selector

Auto phase selector is also provided in the system. If any phase is out of range from the

specified range or during any phase failure, it will select another two healthy phase out of

three phases.

B) Auto Mains Failure and Interlock

PIU is based on world most advance micro controller system with all true RMS

measurement of voltages to ensure correct analysis at right time for trouble free

operation. The system is supported with its own charger and SMF battery to ensure

further reliability in all possible conditions. Electrical interlock & Mechanical

Interlock is also provided using best electromechanical assemblies to avoid any

electrical fault during Micro controller Failure or mishandling of systems. Micro

Controller provides complete DG controls & Monitors the DG activity depending

Upon Various Conditions.

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2) AC Distribution Panel

Fig 6

The AC Distribution panel is provided for load termination. There is group of MCBs

provided with finger touch proof terminal of PE for safety and better connection. The

SMPS, Air conditioners, Power Point, Tube Light, and Aviation Lamp etc shall be

connected to the MCBs as per the marked stickers. A temperature sensor is also wiredwith the interface PCB. It is placed in the conduit.

4) Static Line Conditioner

Fig 7

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Acme Line Conditioner is one of the first of its kind of line regulator in world, using most

advance semiconductor and Ferro resonance technology. The equipment facilitates the

user to replace servo stabilizer as well isolation transformer. The equipment operates with

microprocessor- based controller to provide correction of mains even in s. The design ensures the product utilization not only operating the SMPS as the load but most critical load

like air conditioner etc. The system supports to operate on phase-to phase basis to get rid of

neutral problem, as it is very common. The same provides mains utilization even at extreme

low voltage 140V for air-condition operation, hence low utilization of generator which is

costly. There are two line conditioner provided for Auxiliary electrical support system and

SMPS load.

A power conditioner (also known as a line conditioner or power line conditioner) is a device

intended to improve the quality of the power that is delivered to electrical load equipment.

While there is no official definition of a power conditioner, the term most often refers to a

device that acts in one or more ways to deliver a voltage of the proper level and

characteristics to enable load equipment to function properly. In some usages, power

conditioner refers to a voltage regulator with at least one other function to improve power

quality (e.g. power factor correction, noise suppression, transient impulse protection, etc.).

The terms "power conditioning" and "power conditioner" can be misleading, as the word

"power" here refers to the electricity generally rather than the more technical electric power.

Conditioners specifically work to smooth the sinusoidal A.C. wave form and maintain a

constant voltage over varying loads.

Types

An AC power conditioner is the typical power conditioner that provides "clean" AC power to

sensitive electrical equipment. Usually this is used for home or office applications and has up

to 10 or more receptacles or outlets and commonly provides surge protection as well as noise

filtering.

Power line conditioners take in power and modify it based on the requirements of the

machinery to which they are connected. Voltage spikes are most common during power

storms or other malfunctions in the main power lines. The surge protector stops the flow of

electricity from reaching a machine by shutting off the power source.

The term "Power Conditioning" has been difficult to define historically. However, with the

advances in power technology and recognition by IEEE, NEMA, and other standardsorganizations, a new actual engineering definition has now been developed and accepted to

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provide an accurate depiction of this definition. "Power Conditioning" is the ability to filter

the a.c. line signal provided by the power company. "Power Regulation" is the ability to take

a signal from the local power company, turn it into a d.c. signal that will run an oscillator,

which generates a single frequency sine wave, which is determined by your local area needs,

is fed to the input stage of power amplifier, and is then output as what is specified as the ideal

voltage present at any standard wall outlet.

Design

A good quality power conditioner is designed with internal filter banks to isolate the

individual power outlets or receptacles on the power conditioner. This eliminates interference

or "cross-talk" between components. If the application will be a home theater system, the

noise suppression rating listed in the technical specifications of the power conditioner will be

very important. This rating is expressed in decibels (db).

The higher the db rating, the better the noise suppression. Good units start at a rating of about

40-60db for noise filtering.[citation needed] If a device does not state the db rating in its

specs it may be better to move on to a different model or manufacturer.

The power conditioner will also have a "joule" rating. A joule is a measurement of energy or

heat required to sustain one watt for one second, known as a watt second. Since electrical

surges are momentary spikes, the joule rating indicates how much electrical energy the

suppressor can absorb at once before becoming damaged itself. The higher the joule rating,

the greater the protection.

Usages

Power conditioners can vary greatly in specific functionality and size, with both parameters

generally determined by the application. Some power conditioners provide only minimal

voltage regulation while others provide protection from half a dozen or more power quality

problems. Units may be small enough to mount on a printed circuit board or large enough to

protect an entire factory. Small power conditioners are rated in volt-amperes (VA) while

larger units are rated in kilovolt-amperes (kVA).

Ideally electric power would be supplied as a sine wave with the amplitude and frequency

given by national standards (in the case of mains) or system specifications (in the case of a

power feed not directly attached to the mains) with an impedance of zero ohms at all

frequencies.

No real life power feed will ever meet this ideal. Deviations may include:Variations in the peak or RMS voltage are both important to different types of equipment.

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When the RMS voltage exceeds the nominal voltage by 10 to 80% for 0.5 cycle to 1 minute,

the event is called a "swell". A "dip" (in British English) or a "sag" (in American English the two terms are equivalent) is the opposite situation: the RMS voltage is below the nominal

voltage by 10 to 90% for 0.5 cycle to 1 minute.

Random or repetitive variations in the RMS voltage between 90 and 110% of nominal can

produce a phenomenon known as "flicker" in lighting equipment. Flicker is the impression of

unsteadiness of visual sensation induced by a light stimulus on the human eye. A precise

definition of such a voltage fluctuations that produce flicker have been subject to on going

debate in more than one scientific community for many years. Abrupt, very brief increases in

voltage, called "spikes", "impulses", or "surges", generally caused by large inductive loads

being turned off, or more severely by lightning.

"Under voltage" occurs when the nominal voltage drops below 90% for more than 1

minute. The term "brownout" in common usage has no formal definition but is commonly

used to describe a reduction in system voltage by the utility or system operator to decrease

demand or to increase system operating margins.

"Overvoltage" occurs when the nominal voltage rises above 110% for more than 1 minute.

Variations in the frequency

Variations in the wave shape usually described as harmonics Nonzero low-frequency impedance (when a load draws more power, the voltage drops)

Nonzero high-frequency impedance (when a load demands a large amount of current, then

stops demanding it suddenly, there will be a dip or spike in the voltage due to the inductances

in the power supply line)

5) Alarm Interface

Fig 8

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The DG controls shall be extended from CPU to DG battery charger unit to control the

genset for all possible condition. Same provides controlled battery charging of genset. The

potential free alarms shall be extended from CPU to alarm box for monitoring complete unit.

6) Central Supervisory Unit

Central Supervisory Unit is designed to facilitate better interface of man and machine. The

unit is provided with wide screen, glowing LCD to show the status supported with LED

indication. The system can be operated in two modes automatic mode, DG manual mode. The

detailed Usage of Keys / Switches are described below.

i) Power ON/OFF

The system operates in automatic mode when powered ON. The various electrical

parameters like voltage, current, frequency, power plant voltage etc. & system states are

displayed on the LCD, supported with corresponding LEDs. To set the various parameters

refer for factory default setting sheet.

ii) Generator (DG) Manual mode

The system operates in manual mode if the manual mode switch is in ON position. The

system state in this case is Manual mode.

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iii) RS232

The settings in the menu can be down loaded or uploaded through RS232 cable.

Features:

Higher degree of Automation

Microprocessor based Voltage Regulators with wide Working Range

Better efficiency i.e. > 97%

Longer MTBF i.e. 1,00000 hrs.

Better Lightening & Surge Protections

Better DG Control Management

Inbuilt Network Management System (NMS)

Better Input Voltage Correction

Better Alarms & Securities

Automation with remote control of sites with either SMS or GPRS Gateways

Isolation Transformer, AC Distribution Board & Line Conditioning AMF Panel in a

single rack

Utilize Mains under extreme low voltage condition

Applications:

At any telecommunication site as PIU is

An all-in-one system

A highly efficient system

User friendly

Specifically beneficial where input voltage varies tremendously

Specifically beneficial where single- phasing is a frequent occurrence

Specifically beneficial where fast roll outis required

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3.1 3 Phase to 1 Phase

Mains( 3 Phase)

Abbreviation Used:-

APS:- Auto Phase Selector

Select Best two phases out of three phases.

LCU:- Line conditioner unit

They are divided in 2 parts LCU 1& LCU2

Their input is an 2 phase input .

3.2 3 Phase to 3 Phase

In 3 phase to 3 phase PIU we use Contactor instead of APS and Only one Line Conditioner

Unit.

What is Contactor?

In semiconductor testing, contactor can also refer to the specialised socket that connects the

device under test. In process industries a contactor is a vessel where two streams interact, for

example, air and liquid.

A contactor is an electrically controlled switch used for switching a power circuit, similar to a

relay except with higher current ratings. A contactor is controlled by a circuit which has a

much lower power level than the switched circuit.

A

P

S

LCU 1

LCU 2

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Contactors come in many forms with varying capacities and features. Unlike a circuit

breaker, a contactor is not intended to interrupt a short circuit current. Contactors range from

those having a breaking current of several amperes to thousands of amperes and 24 V DC to

many kilovolts. The physical size of contactors ranges from a device small enough to pick up

with one hand, to large devices approximately a meter (yard) on a side.

Contactors are used to control electric motors, lighting, heating, capacitor banks, and other

electrical loads.

A contactor has three components. The contacts are the current carrying part of the contactor.

This includes power contacts, auxiliary contacts, and contact springs. The electromagnet (or

"coil") provides the driving force to close the contacts. The enclosure is a frame housing the

contact and the electromagnet. Enclosures are made of insulating materials like Bakelite,

Nylon 6, and thermosetting plastics to protect and insulate the contacts and to provide some

measure of protection against personnel touching the contacts. Open-frame contactors may

have a further enclosure to protect against dust, oil, explosion hazards and weather.

Magnetic blowouts use blowout coils to lengthen and move the electric arc. These are

especially useful in DC power circuits. AC arcs have periods of low current, during which the

arc can be extinguished with relative ease, but DC arcs have continuous high current, so blowing them out requires the arc to be stretched further than an AC arc of the same current.

The magnetic blowouts in the pictured Albright contactor (which is designed for DC

currents) more than double the current it can break, increasing it from 600 A to 1,500 A.

Sometimes an economizer circuit is also installed to reduce the power required to keep a

contactor closed; an auxiliary contact reduces coil current after the contactor closes. A

somewhat greater amount of power is required to initially close a contactor than is required to

keep it closed. Such a circuit can save a substantial amount of power and allow the energizedcoil to stay cooler. Economizer circuits are nearly always applied on direct-current contactor

coils and on large alternating current contactor coils.

A basic contactor will have a coil input (which may be driven by either an AC or DC supply

depending on the contactor design). The coil may be energized at the same voltage as the

motor, or may be separately controlled with a lower coil voltage better suited to control by

programmable controllers and lower-voltage pilot devices. Certain contactors have series

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coils connected in the motor circuit; these are used, for example, for automatic acceleration

control, where the next stage of resistance is not cut out until the motor current has dropped.

Operating principle

Unlike general-purpose relays, contactors are designed to be directly connected to high-

current load devices. Relays tend to be of lower capacity and are usually designed for both

normally closed and normally open applications. Devices switching more than 15 amperes or

in circuits rated more than a few kilowatts are usually called contactors. Apart from optional

auxiliary low current contacts, contactors are almost exclusively fitted with normally open

contacts. Unlike relays, contactors are designed with features to control and suppress the arc

produced when interrupting heavy motor currents.

When current passes through the electromagnet, a magnetic field is produced, which attracts

the moving core of the contactor. The electromagnet coil draws more current initially, until

its inductance increases when the metal core enters the coil. The moving contact is propelled

by the moving core; the force developed by the electromagnet holds the moving and fixed

contacts together. When the contactor coil is de-energized, gravity or a spring returns the

electromagnet core to its initial position and opens the contacts.

For contactors energized with alternating current, a small part of the core is surrounded with a

shading coil, which slightly delays the magnetic flux in the core. The effect is to average out

the alternating pull of the magnetic field and so prevent the core from buzzing

Most motor control contactors at low voltages (600 volts and less) are air break contactors;

air at atmospheric pressure surrounds the contacts and extinguishes the arc when interrupting

the circuit. Modern medium-voltage motor controllers use vacuum contactors. High voltage

contactors (greater than 1000 volts) may use vacuum or an inert gas around the contacts.

High-voltage electric locomotives may be isolated from their overhead supply by roof-

mounted circuit breakers actuated by compressed air; the same air supply may be used to

"blow out" any arc that forms.

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Applications

Lighting control

Contactors are often used to provide central control of large lighting installations, such as anoffice building or retail building. To reduce power consumption in the contactor coils,

latching contactors are used, which have two operating coils. One coil, momentarily

energized, closes the power circuit contacts, which are then mechanically held closed; the

second coil opens the contacts.

.

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CHAPTER 4

FREE COOLING UNIT

Free Cooling unit is an electromechanical air handling system to utilize cold ambient air for

thermal management of telecom shelter, electronic enclosures and any other enclosed

systems. It is basically the idea of saving power consumption by using cold ambient air thus

reducing AC Run Hour.

Fig 10

The Air delivery system capacity is selected to take care of various heat load range from 1

KW up to 7.5 KW Keeping 7 degree c Temperature between ambient and room temperature.

The system further provides emergency support options during compressors failure as it can

maintain the temperature at range of ambient.

The FCU system is having the intelligent controllers which can Control AC Controller and

the FCU. All parameters are user settable at the site. Controller will generate alarm for any

fault in AC, high temperature, Low temperature etc.

Free cooling is an economic method of using low outside air temperature to cool the inside

air of an equipment room. This helps in saving energy by reducing running time of Air

conditioner fitted in the equipment room. The solution can be deployed for the telecom

shelters with or without having provision for air conditioners.The system senses shelter temperature, ambient temperature and relative humidity. Based on

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the logical conditions, it provides suitable outputs in the form of 48V DC supply to ventilator

fans and PFC for air conditioner operation.

When (Tin> Temp set) & { (Tin-Tamb). Temp Diff Set} & (RH,Set RH), 48VDC is available

at Output-1 and 2 to run two fan arrays. Simultaneously, PFC condition is available to keep

air-conditioners (if deployed) in off position.

When (Tin-Temp Set) & {(Tin-Tamb)>Temp Diff Set} & (RH.Set RH), 48V DC is not

available at Output-1 and 2 to run two fans but PFC condition is available to keep air-

conditioners (if deployed) in on position. Air conditioners take care of humidity control while

in free cooling option, ingress of humidity is limited by the offered system.

The FCU continuously monitors the ambient temp, room temp and Humidity inside the

shelter .

Main Features if FCU

1. Power Supply :- 48 VDC

2. Analog Inputs

a) Room Temperature Sensor

b) Ambient Temperature Sensor

c)

Input Supply DC voltage Sensing3. Analog outputs

0-10 V DC Fan1 Control Voltage.

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CHAPTER 5

VARIOUS TESTING DONE UNDER TRAINING

Fig 11

A Pictorial View of SMPS Module

Switched-mode power supply

A switched-mode power supply (also switching-mode power supply, SMPS, or simply

switcher ) is an electronic power supply unit (PSU) that incorporates a switching regulator

in order to provide the required dc output voltage.

Terminology

Although the term "power supply" has been in use since radios were first powered from the

line/mains that does not mean that it is a source of power, in the sense that a battery provides

power. It is simply a device that (usually) accepts commercial AC power and provides one or

more DC outputs. It would be more correctly referred to as a power converter, but long usage

has established the term.

Explanation

Whilst a linear regulator maintains the desired output voltage by dissipating excess power in

a pass power transistor , the switched-mode power supply switches a power transistor

between saturation(full on) and cut off (completely off) with a variable duty cycle whose

average is the desired output voltage. It switches at a much higher frequency (tens to

hundreds of kHz) than that of the AC line (mains). This means that the transformer that it

feeds can be much smaller than one connected directly to the line/mains. Switching creates a

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rectangular waveform that typically goes to the primary of the transformer .Usually several

secondarys feed rectifiers, series inductors, and filter capacitors to provide various DCoutputs with low ripple.

Advantages

The main advantage of this method is greater efficiency because the switching transistor

dissipates little power when it is outside of its active region (i.e., when the transistor actslike

a switch and either has a negligible voltage drop across it or a negligible currentthrough it).

Other advantages include smaller size and lighter weight (from the elimination of low

frequency transformers which have a high weight) and lower heat generation due to higher

efficiency. Disadvantages include greater complexity, the generation of high-amplitude, high-

frequency energy that the low-pass filter must block to avoid electromagnetic

interference(EMI), and a ripple voltage at the switching frequency and the harmonic

frequencies thereof. Very low cost SMPS may couple electrical switching noise back onto the

mains power line, causing interference with A/V equipment connected to the same phase.

Non power-factor-corrected SMPSs also cause harmonic distortion.

Classification

SMPS can be classified into four types according to the input and output waveforms:

AC in, DC out : rectifier ,off-line converter input stage

DC in , DC out: voltage converter , or current converter, or DC to DC converter

AC in, AC out: frequency changer, cyclo converter, transformer

DC in, AC out: inverter

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Theory of operation

Fig 12

Block diagram of a mains operated AC-DC SMPS with output voltage regulation

Fig 13

Input rectifier stage

AC, half-wave and full wave rectified signals If the SMPS has an AC input, then the first

stage is to convert the input to DC. This is called rectification. The rectifier circuit can be

configured as a voltage doubler by the addition of a switch operated either manually or

automatically. This is a feature of larger supplies to permit operation from nominally 120 volt

or 240 volt supplies. The rectifier produces an unregulated DC voltage which is then sent to

a large filter capacitor. The current drawn from the mains supply by this rectifier circuit

occurs in short pulses around the AC voltage peaks. These pulses have significant high

frequency energy which reduces the power factor. Special control techniques can be

employed by the following SMPS to force the average input current to follow the sinusoidal

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shape of the AC input voltage thus the designer should try correcting the power factor . An

SMPS with a DC input does not require this stage. An SMPS designed for AC input can often

be run from a DC supply (for 230V AC this would be 330V DC), as the DC passes through

the rectifier stage unchanged. It's however advisable to consult the manual before trying this,

though most supplies are quite capable of such operation even though nothing is mentioned in

the documentation. However, this type of use may be harmful to the rectifier stage as it will

only utilize half of diodes in the rectifier for the full load. This may result in overheating of

these components, and cause them to fail prematurely.

If an input range switch is used, the rectifier stage is usually configured to operate as a

voltage doubler when operating on the low voltage (~120 VAC) range and as a straight

rectifier when operating on the high voltage (~240 VAC) range. If an input range switch isnot used, then a full-wave rectifier is usually used and the downstream inverter stage is

simply designed to be flexible enough to accept the wide range of dc voltages that will be

produced by the rectifier stage. In higher-power SMPSs, some form of automatic ranges

witching may be used.

Inverter stage

The inverter stage converts DC, whether directly from the input or from the rectifier stagedescribed above, to AC by running it through a power oscillator, whose output transformer is

very small with few windings at a frequency of tens or hundreds of kilohertz(kHz). The

frequency is usually chosen to be above 20 kHz, to make it in audible to humans. The output

voltage is optically coupled to the input and thus very tightly controlled. The switching is

implemented as a multistage (to achieve high gain)MOSFET amplifier. MOSFETs are a type

of transistor with a low on-resistance and a high current- handling capacity. Since only the

last stage has a large duty cycle, previous stages can be implemented by bipolar transistorsleading to roughly the same efficiency. The second last stage needs to be of a complementary

design, where one transistor charges the last MOSFET and another one discharges the

MOSFET. A design using a resistor would run idle most of the time and reduce efficiency.

All earlier stages do not weight in to efficiency because power decreases by a factor of 10 for

every stage (going backwards)and thus the earlier stages are responsible for at most 1% of the

efficiency. This section refers to the block marked Chopper in the block diagram.

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Voltage converter and output rectifier

If the output is required to be isolated from the input, as is usually the case in mains power

supplies, the inverted AC is used to drive the primary winding of a high-frequency

transformer. This converts the voltage up or down to the required output level on its

secondary winding. The output transformer in the block diagram serves this purpose. If a DC

output is required, the AC output from the transformer is rectified. For output voltages above

ten volts or so, ordinary silicon diodes are commonly used. For lower voltages, Schottky

diodes are commonly used as the rectifier elements; they have the advantages of faster

recovery times than silicon diodes (allowing low-loss operation at higher frequencies) and a

lower voltage drop when conducting. For even lower output voltages ,MOSFETs may be

used as synchronous rectifiers; compared to Schottky diodes, these have even lower

conducting state voltage drops. The rectified output is then smoothed by a filter consisting of

inductors and capacitors. For higher switching frequencies, components with lower

capacitance and inductance are needed. Simpler, non-isolated power supplies contain an

inductor instead of a transformer. This type includes boost converters, buck converters, and

the so called buck-boost converters. These belong to the simplest class of single input, single

output converters which utilize one inductor and one active switch. The buck converter

reduces the input voltage in direct proportion to the ratio of conductive time to the totalswitching period, called the duty cycle. For example an ideal buck converter with a 10 V

input operating at a 50% duty cycle will produce an average output voltage of 5 V. A

feedback control loop is employed to regulate the output voltage by varying the duty cycle to

compensate for variations in input voltage. The output voltage of a boost converter is always

greater than the input voltage and the buck-boost output voltage is inverted but can be greater

than, equal to, or less than the magnitude of its input voltage. There are many variations and

extensions tothis class of converters but these three form the basis of almost all isolated andnon-isolated DC to DC converters. By adding a second inductor the uk and SEPICconverters can be implemented, or, by adding additional active switches, various bridge

converters can be realised .Other types of SMPSs use a capacitor -diode voltage multiplier

instead of inductors and transformers. These are mostly used for generating high voltages at

low currents

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Regulation

A feedback circuit monitors the output voltage and compares it with a reference voltage,

which is set manually or electronically to the desired output. If there is an error in the output

voltage, the feedback circuit compensates by adjusting the timing with which the MOSFETs

are switched on and off. This part of the power supply is called the switching regulator. The

Chopper controller shown in the block diagram serves this purpose. Depending on

design/safety requirements, the controller may or may not contain an isolation mechanism

(such a sopto-couplers) to isolate it from the DC output. Switching supplies in computers,

TVs and VCRs have these opto-couplers to tightly control the output voltage.

Open-loop regulators

do not have a feedback circuit. Instead, they rely on feeding a constant voltage to the input of

the transformer or inductor, and assume that the output will be correct. Regulated designs

compensate for the parasitic capacitance of the transformer or coil. Monopolar designs also

compensate for the magnetic hysteresis of the core. The feedback circuit needs power to run

before it can generate power, so an additional non-switching power-supply for stand-by is

added.

Transformer design

SMPS transformers run at high frequency. Most of the cost savings (and space savings) inoff-

line power supplies come from the fact that a high frequency transformer is muchsmaller than

the 50/60 Hz transformers formerly used. There are several differences in the design of

transformers for 50 Hz vs 500 kHz. Firstly allow frequency transformer usually transfers

energy through its core (soft iron), while the (usually ferrite) core of a high frequency

transformer limits leakage. Since the wave forms in a SMPS are generally high speed (PWMsquare waves), the wiring must be capable of supporting high harmonics of the base

frequency due to the skin effect, which is a major source of power loss.

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Fig 14

5.1 Load Shutter TestingLoad Shutter as the Name Indicates that it is used to shut the load at the telecom Site. When

there is some problem at the site it is used without the need of any specialized worker at the

site.In the shutter a modem is used in which a network providing SIM is placed. Various

Commands can be sent through another SIM and load shutter can be controlled. There are

various Commands for Load Shutter. Mainly in Load Shutter GSM Module is Placed . For

Carrying out the testing process we simply use a 100 watt bulb to check that load shutter is

working or not.

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3. Meier, Alexandra von (2006). Electric Power Systems: A Conceptual Introduction .

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4. Sittig, Roland; Roggwiller, P. (1982). Semiconductor Devices for Power Conditioning .

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5 .http://www.pragatielectrocom.com/free-cooling-system.html

6 .www.acme.in

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8.Terrell Croft and Wilford Summers (ed), American Electricans' Handbook, Eleventh

Edition, McGraw Hill, New York (1987) ISBN 0-07-013932-6 page 7-124

9. Croft, page 7-125

10. Ragnar Holm (1958, 3rd Edition). Electric Contacts Handbook . Springer-Verlag, Berlin /

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11. "Lab Note #105 Contact Life - Unsuppressed vs. Suppressed Arcing ". Arc Suppression

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12. Hammond, Rolt (1968). "Development of electric traction". Modern Methods of Railway

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13.Ransome-Wallis, Patrick (1959). "Electric motive power". Illustrated Encyclopedia of

World Railway Locomotives . London: Hutchinson. p. 173. ISBN 0-486-41247-4.

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14 .http://www.nema.org/engineering/icsstandards.html